Research on hardware acceleration of multi-longitudinal mode laser beat frequency demodulation system

Real-time monitoring of downhole temperature and pressure variations plays a crucial role in ensuring well safety and effective reservoir management in oil and gas exploration. Leveraging the fiber Bragg grating technology with multilongitudinal mode laser frequency modulation and incorporating side-hole optical fiber grating sensors enable highresolution monitoring of well temperature and pressure. Utilizing digital demodulation technology to decipher multilongitudinal mode frequency modulation signals addresses challenges associated with traditional spectrum analyzers, such as structural complexity and poor stability. However, current research lacks dedicated demodulation methods for multi-longitudinal mode laser frequency modulation signals, apart from general software processing approaches. This paper introduces a hardware acceleration approach for frequency modulation demodulation. It outlines a hardware acceleration architecture based on a Field-Programmable Gate Array (FPGA). This architecture implements hardware circuits for various demodulation processes, including all-phase fast Fourier transform and phase difference method spectrum correction. It adopts a pipeline architecture and multi-clock domain processing to enhance signal processing efficiency. The system ultimately achieves a demodulation frequency of 15.259 kHz, a demodulation delay of 0.143ms, and a data utilization rate of 100%.